# Hidden (’Blind’) Mailbox Extension Number Programming

Dial strings to transfer to the mailbox extension number are contained in the pre-DN and post-DN dial strings that are programmed into the configuration by the technician.

NP Receptionist programming adds certain characters to the end of the mailbox extension number. These "hidden" characters depend on the mailbox’s treatment type:

- If the mailbox has an extension treatment type, NP Receptionist automatically appends a G (wait for a person or computer tone greeting) unless you insert an H (hang up) at the end of the dial string.

- If the mailbox has a trunk treatment type, the hidden character depends on the connect criteria chosen:

  - If the connect criteria is "Tone," a T (wait for dial tone) is appended.

  - If the connect criteria is "Ring," a special character that tells NP Receptionist to wait for a single ring is appended.

  - If the connect criteria is "Cut through," NP Receptionist checks whether the last character in the mailbox extension number is an H. If it is not, NP Receptionist automatically hangs up after it outdials the dial string.